Turbine engines are used as the primary power source for many types of aircraft. Most turbine engines generally follow the same basic power generation procedure. Air is ingested into the fan section of an engine and is directed against at least one set of stationary vanes toward axial and/or radial compressors. The compressed air is mixed with fuel and burned, and the expanding hot combustion gases are directed against another set of stationary vanes in the engine. The vanes deflect the high velocity gas flow so as to impinge on turbine blades mounted on a rotatable turbine disk. The force of the impinging gas causes the turbine disk to spin at high speed to create power.
As mentioned above, stationary vanes are disposed along one or more sections of the air flow path. The stationary vanes may be part of an assembly, such as an air diffuser assembly or other component, and they typically extend between an outer annular housing and an inner annular housing. To improve structural integrity of the assembly, the vanes and housings may be integrally cast. Additionally, the assembly may be made from a superalloy, including, but not limited to, nickel-based, cobalt-based, and iron-based superalloys.
Although integrally cast assemblies offer many advantages, they may have drawbacks. For example, the repair of these assemblies may present challenges. Specifically, foreign objects such as sand, dirt, and other such debris may impinge against a leading edge of a vane and cause damage. However, because the individual vanes are permanently attached to the housings, the damaged vane may not be easily removed for repair. Additionally, the superalloys from which the assemblies may be made are generally difficult to weld successfully. For example, welding techniques often include heating the assembly to high temperatures, ranging from 1800° F. to 2000° F. (980° C. to 1095° C.), which may cause the vanes or housings to experience distorting and deformation rendering the vane unusable for further engine service. Moreover, some vanes have complex leading edge geometries thereby making it difficult to deposit filler or cladding material thereon. Braze repair may be another option, however, precision process control may then be needed to prevent distortion of the assembly under braze thermal cycles.
Hence, a method for repairing a vane assembly is desired that may be used to fully restore the geometry, dimension, and desired properties of degraded vanes. Additionally, it is desirable to repair the vane assembly without causing distortion and/or damage to the vane. Additionally, it is desirable to have a repair method that is less costly as compared to the alternative of replacing worn parts with new ones.